1. Field of the Invention
The present invention relates to a manufacturing method of an organic semiconductor device using an organic semiconductor transistor.
2. Description of the Related Art
A semiconductor transistor typified by TFT shows the current trend towards spreading of its applications along with the development of display devices. Such a semiconductor transistor functions as a switching element when the electrodes are connected through a semiconductor material.
As the semiconductor material used for the semiconductor transistor, inorganic semiconductor materials such as silicon (Si), gallium arsenic (GaAs) and indium gallium arsenic (InGaAs) are used. Semiconductor transistors using such an inorganic semiconductor are also used for display TFT array substrates of liquid crystal display devices which have been widely spread in recent years.
On the other hand, organic semiconductor materials made of organic compounds are known as the semiconductor material. Organic semiconductor materials have an advantage in that: they are allowed to be increased in area at a lower cost than those using the inorganic semiconductor materials, and they can be formed on a flexible plastic substrate and are also stable against mechanical impact. Therefore, active studies are being made as to technologies assumed to be applied display devices such as flexible displays typified by electronic paper in the next generation.
In the meantime, along with a rapid spread of and an increase in the size of thin type display devices which have been recently developed, it is demanded of organic semiconductor devices using an organic semiconductor material to be mass-producible with high productivity in an industrial production process. However, no method has been established yet which is capable of producing an organic semiconductor transistor using an organic semiconductor material at high productivity in contrast to conventional transistors using an inorganic semiconductor material. This is caused by the characteristics common to many organic semiconductor materials.
Specifically, the organic semiconductor materials have the characteristics that they develop excellent semiconductor characteristics when they are made into films under heating. Therefore, when semiconductor transistors are produced using these semiconductor materials, it is necessary to use a method in which it is patterned after a layer made of the organic semiconductor material is formed.
As the method of patterning the layer formed of the organic semiconductor material, a photoresist method using a photoresist is usually used (for example, see Japanese Patent Application Laid-Open No. 2006-58497). Such a photoresist method is superior in the point that a layer made of an organic semiconductor material can be patterned into a desired pattern with high accuracy. However, this method has the problem that it is inferior in productivity because of complicated steps involved.
This gives rise to the problem that organic semiconductor devices using the organic semiconductors cannot be produced industrially with high efficiency though they are known to have high usability.